Engine Management Light Came on today

[kuljit55]

Hi guys i have a 2003 e12 corolla 1.6 manunal petrol corolla at 91k. Its been so hot today 35°c here in Leicester and i had my AC on all day, near the end of the day my engine maintainence light came on, and it didnt turn off even after a 20mins engine turn off. I made a 30 mile journey to nottingham at 70mph and car drive as normal. Any ideas why the light came on? Thanks

[SanaYusuf]

Only way is to get fault code(S) read.

[kuljit55]

Only way is to get fault code(S) read.

I will do that off course but meanwhile was wondering using the AC whole day on a hot day could be the cause..

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[oldcodger]

As said, you need to get a garage to read out the code, they will also be able to reset/clear the error light/codes, or you can do it yourself by buying a suitable ecu code reader or to just clear the error light and codes. you can disconnect the Battery for 10 mins, though that may also cause the ecu to go into learning mode for the first few miles ( rough running at low revs )

[Anthony Poli]

9 hours ago, kuljit55 said:

I will do that off course but meanwhile was wondering using the AC whole day on a hot day could be the cause..

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That shouldn't be the reason, AC systems have been around for a long time and the only difference to having on or turned off is mpg.

I would get a code reader and at least you would get a good idea what sort of problem it is.

If the problem is a one off, the system should reset the light itself after so many engine starts after the problem is cleared.

[kuljit55]

I will do that off course but meanwhile was wondering using the AC whole day on a hot day could be the cause..

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That shouldn't be the reason, AC systems have been around for a long time and the only difference to having on or turned off is mpg.

I would get a code reader and at least you would get a good idea what sort of problem it is.

If the problem is a one off, the system should reset the light itself after so many engine starts after the problem is cleared.

So i took it for a checkup and the computer gave me the following codes on the report:

P0420 - Catalyst system effeciency below threshold (bank 1) - historical

P0420 - Catalyst system effeciency below threshold (bank 1) - current

The mechanic reckons its the Lambda sensor (pre-cat side)

He also said its been on in the past and resetted, he said it might have triggered due to hot weather. He reset it and the light is now off, he suggested to keep driving to see if it comes on again. If it does then he said most probably the Lambda sensor will need replacing, i have drove 5miles so far and its not come on.

Any other advice or ideas to consider at this stage? Also which brand lambda sensor would be recconmended?? Thanks

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[Anthony Poli]

I had an O2 sensor which started off like that, in the end I took it into Mr T's.

 

[kuljit55]

I had an O2 sensor which started off like that, in the end I took it into Mr T's.

 

Did your light come back on again before you got the o2 sensor replaced?

Was it the front of cat sensor or rear cat sensor that needed replacing? Also how much did it cost you and is the problem sorted now? Thanks

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[Anthony Poli]

The problem came back 12 months later and then it was  more regular. It was the after the cat, at one point it did show up 3 error codes, all associated with the same sensor. I can't quite remember how much dealer charged, must have between 250 to 350. I suspect it was when the supermarkets had imported the cheap petrol that was damaging peoples sensors. That's going back a good few years ago.

The car's mpg was back to normal after the sensor was replaced.

[kuljit55]

The problem came back 12 months later and then it was  more regular. It was the after the cat, at one point it did show up 3 error codes, all associated with the same sensor. I can't quite remember how much dealer charged, must have between 250 to 350. I suspect it was when the supermarkets had imported the cheap petrol that was damaging peoples sensors. That's going back a good few years ago.

The car's mpg was back to normal after the sensor was replaced.

So the problem came back after you replaced the sensor? What did the mechanic say it was that you have to get replaced then? Also did your car feel abit sluggish when the light was on at start? Thanks

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[Anthony Poli]

15 minutes ago, kuljit55 said:

So the problem came back after you replaced the sensor? What did the mechanic say it was that you have to get replaced then? Also did your car feel abit sluggish when the light was on at start? Thanks

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I'm sorry if my post was confusing, the fault was fixed after the sensor was replaced. I was trying to describe how the sensor started failing and how long we waited until getting the problem fixed.

I watched the sensor deteriorate over 2 years, until it actually caused a big enough change in the mpg. 

 

[kuljit55]

So the problem came back after you replaced the sensor? What did the mechanic say it was that you have to get replaced then? Also did your car feel abit sluggish when the light was on at start? Thanks

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I'm sorry if my post was confusing, the fault was fixed after the sensor was replaced. I was trying to describe how the sensor started failing and how long we waited until getting the problem fixed.

I watched the sensor deteriorate over 2 years, until it actually caused a big enough change in the mpg. 

 

Thats great, would you know which brand Lambda Sensor you used on your Corolla? Im getting mixed answers online. Thanks

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[Anthony Poli]

3 minutes ago, kuljit55 said:

I'm sorry if my post was confusing, the fault was fixed after the sensor was replaced. I was trying to describe how the sensor started failing and how long we waited until getting the problem fixed.

I watched the sensor deteriorate over 2 years, until it actually caused a big enough change in the mpg. 

 

 

Thats great, would you know which brand Lambda Sensor you used on your Corolla? Im getting mixed answers online. Thanks

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I'm sorry I can't tell you which brand, had the sensor changed at a Toyota dealer.

[roks]

Kuljit,

I had this P0420 code show begining of 2013, probably around the 95k miles, I reset the code and didnt show until end of 2014 and then I would reset and wont see it for 6 months etc...since last year I gave up reseting cant be bothered since it comes back more often, only reset it before the MOT.

What I did notice is beofre the code comes on the car is slugish for couple of minutes and I paniced at the first couple of times, then back to normal. The car drives normal with the light on, mpg normal.

I beleive you need a denso brand, if you go to denso website and enter your reg it will give you the denso part number, £60-75.

Anthony,

  Was it is a P0420 you got? I didnt replace it because I wasnt sure if it was the o2 sensor, there are more specific ones for the o2 sensors.

Please confirm it was the rear (post cat) O2 sensor you replaced? I am going to try and replace that sensor.

Thanks.

[Anthony Poli]

41 minutes ago, roks said:

Kuljit,

I had this P0420 code show begining of 2013, probably around the 95k miles, I reset the code and didnt show until end of 2014 and then I would reset and wont see it for 6 months etc...since last year I gave up reseting cant be bothered since it comes back more often, only reset it before the MOT.

What I did notice is beofre the code comes on the car is slugish for couple of minutes and I paniced at the first couple of times, then back to normal. The car drives normal with the light on, mpg normal.

I beleive you need a denso brand, if you go to denso website and enter your reg it will give you the denso part number, £60-75.

Anthony,

  Was it is a P0420 you got? I didnt replace it because I wasnt sure if it was the o2 sensor, there are more specific ones for the o2 sensors.

Please confirm it was the rear (post cat) O2 sensor you replaced? I am going to try and replace that sensor.

Thanks.

Hi Roks,

I just found the screenshots of my phone app showing my codes, I had both P0130 & P0134. Viewing both sensors live, i could see that it was the sensor, that was failing.

[roks]

Thanks Anthony, just as I thought, these are specific o2 sensor codes so they are prety much 100% where the fault is. P0420 is a bit of a tricky one, although it says cat below efficiency, at mot its squeeky clean.

It could be the rear sensor because its not always flat in the middle like its supposed to be. Any chance you could do one of these screen for your o2 sensor 2 after engine is at operating temp? One idle rpm and another at 2500rpm?

Also, when you take it up to 2500rpm, does the graph change during the climb to 2500?

Cheers.

[kuljit55]

Thanks Anthony, just as I thought, these are specific o2 sensor codes so they are prety much 100% where the fault is. P0420 is a bit of a tricky one, although it says cat below efficiency, at mot its squeeky clean.

It could be the rear sensor because its not always flat in the middle like its supposed to be. Any chance you could do one of these screen for your o2 sensor 2 after engine is at operating temp? One idle rpm and another at 2500rpm?

Also, when you take it up to 2500rpm, does the graph change during the climb to 2500?

Cheers.

Thanks Anthony, just as I thought, these are specific o2 sensor codes so they are prety much 100% where the fault is. P0420 is a bit of a tricky one, although it says cat below efficiency, at mot its squeeky clean. It could be the rear sensor because its not always flat in the middle like its supposed to be. Any chance you could do one of these screen for your o2 sensor 2 after engine is at operating temp? One idle rpm and another at 2500rpm?

Also, when you take it up to 2500rpm, does the graph change during the climb to 2500?

Cheers.

That is what i got in the report, the mechanic suggested its most likely the Lambda sensor. By the way, if it is that, will a Denso branded sensor be fine? Also once replaced, will i need to get the light resetted again? And if so is it recconmended to do it immediately or i can reset it after a day or so?? Thanks

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[Anthony Poli]

1 hour ago, roks said:

Thanks Anthony, just as I thought, these are specific o2 sensor codes so they are prety much 100% where the fault is. P0420 is a bit of a tricky one, although it says cat below efficiency, at mot its squeeky clean.

It could be the rear sensor because its not always flat in the middle like its supposed to be. Any chance you could do one of these screen for your o2 sensor 2 after engine is at operating temp? One idle rpm and another at 2500rpm?

Also, when you take it up to 2500rpm, does the graph change during the climb to 2500?

Cheers.

I'm sure somebody else on here can help you on here, as my current car is a hybrid and I'm not sure how easy it would be control rpm while stationary.

Originally I found typical graphs via search on google that i used to compare with mine.

At operating temp and idling, sensor 1 changes at the similar rate to a hear beat (high or low) and sensor 2 changes slower (much lower change in voltage, roughly around the middle).

While driving I did notice sensor 2 would either be stuck at high or low for minutes.

 

 

[roks]

Kuljit, I would reset it straight after replacing sensor, I am told toyota use denso so should be fine.

Let us know if that solves the problem.

 

Anthony, thanks I thought you still had the car. But you did help in confirm something, mine stick low on idle and high when reving to 2500. when driving, its low for a bit then high and changes but still oscillating slowly.

[kuljit55]

Kuljit, I would reset it straight after replacing sensor, I am told toyota use denso so should be fine.

Let us know if that solves the problem.

 

Anthony, thanks I thought you still had the car. But you did help in confirm something, mine stick low on idle and high when reving to 2500. when driving, its low for a bit then high and changes but still oscillating slowly.

Managed to get the Lambda sensor replaced today. The light did not come off automatically, so the mechanic did reset it and said hopefully it shouldnt come back on. So fingers crossed at this point. Will report back if problem re-occurs. Thank you.

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[roks]

Thanks for the update Kuljit, do keep us updated after some time even to say it hasn't come back yet.

[Anthony Poli]

20 minutes ago, kuljit55 said:

Managed to get the Lambda sensor replaced today. The light did not come off automatically, so the mechanic did reset it and said hopefully it shouldnt come back on. So fingers crossed at this point. Will report back if problem re-occurs. Thank you.

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The way I understand things, once the fault is cleared, the ECU waits until you have started the engine a couple times before it resets the light. I did see this happen during a shopping trip with several stops.

So I'm sure you will have no worries about the light coming back on.

[roks]

Just as a fyi, I did replace both of the o2 sensors, I didnt notice any faster readings or anything, and the downstream sensor reading was same as well, flat at 0.8v or 0.2v, not lke other cars where its at 0.45v....but no engine light yet, its done 500miles sor far.

[Anthony Poli]

20 minutes ago, roks said:

Just as a fyi, I did replace both of the o2 sensors, I didnt notice any faster readings or anything, and the downstream sensor reading was same as well, flat at 0.8v or 0.2v, not lke other cars where its at 0.45v....but no engine light yet, its done 500miles sor far.

I take it the 500 miles was with several journeys.

Does the car feel any better, has the mpg changed?

[roks]

Yes, several journeys, around 170miles is motorway speed, the rest is dual carriage way and local town driving.

The dash board mpg has not settled as I disconnected the Battery after replacing both the sensors, its currently at 35mpg.

I've not noticed any different behaviors and not had a chance to connect to Techstream to look at the fuel trims.